Peripheral opioid receptor antagonists and uses thereof

ABSTRACT

The present invention provides a compound of formula I: 
                         
wherein X − , R 1 , and R 2  are as defined herein, and compositions thereof; useful as a peripheral mu opioid receptor antagonist.

RELATED APPLICATIONS

The present application is a continuation of U.S. patent application Ser. No. 12/594,139, filed Dec. 9, 2009, which is a 35 U.S.C. §371 national stage filing of International Application No. PCT/U.S.2008/58729, filed on Mar. 28, 2008, which claims priority to U.S. Provisional Patent Application No. 60/920,722, filed Mar. 29, 2007, the entirety of each of which applications are hereby incorporated herein by reference.

BACKGROUND OF THE INVENTION

Opioids are widely used in patients with advanced cancers and other terminal diseases to lessen suffering. Opioids are narcotic medications that activate opioid receptors located in the central nervous system to relieve pain. Opioids, however, also react with receptors outside of the central nervous system, resulting in side effects including constipation, nausea, vomiting, urinary retention, and severe itching. Most notable are the effects in the gastrointestinal tract (GI) where opioids inhibit gastric emptying and propulsive motor activity of the intestine, thereby decreasing the rate of intestinal transit and producing constipation. The effectiveness of opioids for pain is often limited due to resultant side effects, which can be debilitating and often cause patients to cease use of opioid analgesics.

In addition to analgesic opioid induced side effects, studies have suggested that endogenous opioid compounds and receptors may also affect activity of the gastrointestinal (GI) tract and may be involved in normal regulation of intestinal motility and mucosal transport of fluids in both animals and man. (Koch, T. R. et al, Digestive Diseases and Sciences 1991, 36, 712-728; Schuller, A. G. P., et al., Society of Neurosoience Abstracts 1998, 24, 524, Reisine, T., and Pasternak, G., Goodman & Gilman's The Pharmacological Basis of Therapeutics Ninth Edition 1996, 521-555 and Bagnol, D., et al., Regul. Pept. 1993, 47, 259-273). Thus, an abnormal physiological level of endogenous compounds and/or receptor activity may lead to bowel dysfunction.

For example, patients who have undergone surgical procedures, especially surgery of the abdomen, often suffer from a particular bowel dysfunction, called post-operative (or post-surgical) ileus, that may be caused by fluctuations in natural opioid levels. Similarly, women who have recently given birth commonly suffer from post-partum ileus, which is thought to be caused by similar natural opioid fluctuations as a result of birthing stress. Gastrointestinal dysfunction associated with post-operative or post partum ileus can typically last for 3 to 5 days, with some severe cases lasting more than a week. Administration of opioid analgesics to a patient after surgery, which is now an almost universal practice, may exacerbate bowel dysfunction, thereby delaying recovery of normal bowel function, prolonging hospital stays, and increasing medical care costs.

Opioid receptor antagonists such as naloxone, naltrexone, and nalmefene, have been studied as a means of antagonizing undesirable peripheral effects of opioids. However, these agents act not only on peripheral opioid receptors, but also on central nervous system sites, so that they sometimes reverse the beneficial analgesic effects of opioids, or cause symptoms of opioid withdrawal. Preferable approaches for use in controlling opioid-induced side effects include administration of peripheral opioid receptor antagonist compounds that do not readily cross the blood-brain barrier. For example, the peripheral μ opioid receptor antagonist compound methylnaltrexone and related compounds have been disclosed for use in curbing opioid-induced side effects in patients (e.g., constipation, pruritus, nausea, and/or vomiting). See, e.g., U.S. Pat. Nos. 5,972,954, 5,102,887, 4,861,781, and 4,719,215; and Yuan, C. -S. et al. Drug and Alcohol Dependence 1998, 52, 161. Similarly, peripherally selective piperidine-N-alkylcarboxylate and 3,4-dimethyl-4-aryl-piperidine opioid receptor antagonists have been described as being useful for treatment of opioid-induced side effects constipation, nausea or vomiting, as well as irritable bowel syndrome and idiopathic constipation. See, e.g., U.S. Pat. Nos. 5,250,542, 5,434,171, 5,159,081, and 5,270,328.

It would be desirable to provide peripheral μ opioid receptor antagonist compounds for administration to a patient in need of treatment for any of the above-mentioned disorders.

SUMMARY

The present invention provides a compound of formula I:

wherein X⁻, R¹, and R² are as defined and described herein, and the compound is in the (R) configuration with respect to the nitrogen. The present invention also provides pharmaceutical compositions and formulations comprising a compound of formula I. The provided compounds are peripheral μ opioid receptor antagonists and are therefore useful for the treatment, prevention, amelioration, delay or reduction of severity and/or incidence of side effects associated with opioid administration, such as, for example, gastrointestinal dysfunction (e.g., inhibition of intestinal motility, constipation, GI sphincter constriction, nausea, emesis (vomiting), biliary spasm, opioid bowel dysfunction, colic), dysphoria, pruritus, urinary retention, depression of respiration, papillary constriction, cardiovascular effects, chest wall rigidity and cough suppression, depression of stress response, and immune suppression associated with administration of narcotic analgesia, etc, or combinations thereof. Other uses of provided compounds are set forth infra.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts the HPLC chromatogram of compound II-1,

FIG. 2 depicts the UV spectrum of compound II-1.

FIG. 3 depicts the ¹H NMR spectrum of compound II-1.

DETAILED DESCRIPTION OF CERTAIN EMBODIMENTS OF THE INVENTION

1. Compounds and Definitions

In certain embodiments, the present invention provides a compound of formula I:

wherein:

-   R¹ and R² are each independently C₁₋₆ aliphatic; and -   X⁻ is a suitable anion.

The term “aliphatic” or “aliphatic group”, as used herein, means a straight-chain (i.e., unbranched) or branched hydrocarbon chain that is completely saturated or that contains one or more units of unsaturation, or a monocyclic hydrocarbon that is completely saturated or that contains one or more units of unsaturation, but which is not aromatic (also referred to herein as “carbocycle” “cycloaliphatic” or “cycloalkyl”), that has a single point of attachment to the rest of the molecule. In certain embodiments, an aliphatic group contains 1-4 aliphatic carbon atoms, and in yet other embodiments, an aliphatic group contains 1-3 aliphatic carbon atoms. In some embodiments, “cycloaliphatic” (or “carbocycle”) refers to a monocyclic C₃-C₆ hydrocarbon that is completely saturated or that contains one or more units of unsaturation, but which is not aromatic, that has a single point of attachment to the rest of the molecule. Such cycloaliphatic groups include cycloalkyl, cycloalkenyl, and cycloalkynyl groups. Suitable aliphatic groups include, but are not limited to, linear or branched alkyl, alkenyl, alkynyl groups and hybrids thereof such as (cycloalkyl)alkyl, (cycloalkenyl)alkyl or (cycloalkyl)alkenyl. Exemplary aliphatic groups include allyl, vinyl, cyclopropylmethyl, methyl, ethyl, isopropyl, and the like.

The term “unsaturated,” as used herein, means that a moiety has one or more units of unsaturation.

The term “lower alkyl,” as used herein, refers to a hydrocarbon chain having up to 4 carbon atoms, preferably 1 to 3 carbon atoms, and more preferably 1 to 2 carbon atoms. The term “alkyl” includes, but is not limited to, straight and branched chains such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, or t-butyl.

As used herein, an “effective amount” of a compound or pharmaceutically acceptable composition can achieve a desired therapeutic and/or prophylactic effect. In some embodiments, an “effective amount” is at least a minimal amount of a compound, or composition containing a compound, which is sufficient for treating one or more symptoms of a disorder or condition associated with modulation of peripheral μ opioid receptors, such as side effects associated with opioid analgesic therapy (e.g., gastrointestinal dysfunction (e.g., dysmotility constipation, etc.), nausea, emesis, (e.g., nausea), etc.). In certain embodiments, an “effective amount” of a compound, or composition containing a compound, is sufficient for treating one or more symptoms associated with, a disease associated with aberrant endogenous peripheral opioid or μ opioid receptor activity (e.g., idiopathic constipation, ileus, etc.).

The term “subject”, as used herein, means a mammal and includes human and animal subjects, such as domestic animals (e.g., horses, dogs, cats, etc.).

The terms “suffer” or “suffering” as used herein refers to one or more conditions that a patient has been diagnosed with, or is suspected to have.

The terms “treat” or “treating,” as used herein, refers to partially or completely alleviating, inhibiting, delaying onset of, preventing, ameliorating and/or relieving a disorder or condition, or one or more symptoms of the disorder or condition.

“Therapeutically active agent” or “active agent” refers to a substance, including a biologically active substance; that is useful for therapy (e.g., human therapy, veterinary therapy), including prophylactic and therapeutic treatment. Therapeutically active agents include organic molecules that are drug compounds, peptides, proteins, carbohydrates, monosaccharides, oligosaccharides, polysaccharides, nucleoprotein, mucoprotein, lipoprotein, synthetic polypeptide or protein, small molecules linked to a protein, glycoprotein, steroid, nucleic acid, DNA, RNA, nucleotide, nucleoside, oligonucleotides, antisense oligonucleotides, lipid, hormone, and vitamin. Therapeutically active agents include any substance used as a medicine for treatment, prevention, delay, reduction or amelioration of a disease, condition, or disorder. Among therapeutically active agents useful in the formulations of the present invention are opioid receptor antagonist compounds, opioid analgesic compounds, and the like. Further detailed description of compounds useful as therapeutically active agents is provided below. A therapeutically active agent includes a compound that increases the effect or effectiveness of a second compound, for example, by enhancing potency or reducing adverse effects of a second compound.

The expression “unit dosage form” as used herein refers to a physically discrete unit of inventive formulation appropriate for the subject to be treated. It will be understood, however, that the total daily usage of the compositions of the present invention will be decided by the attending physician within the scope of sound medical judgment. The specific effective dose level for any particular subject or organism will depend upon a variety of factors including the disorder being treated and the severity of the disorder, activity of specific active agent employed; specific composition employed; age, body weight, general health, sex and diet of the subject; time of administration, and rate of excretion of the specific active agent employed; duration of the treatment; drugs and/or additional therapies used in combination or coincidental with specific compound(s) employed, and like factors well known in the medical arts.

2. Description of Exemplary Compounds

As described generally above, the present invention provides a compound of formula I:

wherein:

-   R¹ and R² are each independently C₁₋₆ aliphatic; and -   X⁻ is a suitable anion.

One of ordinary skill in the art will recognize that the nitrogen atom depicted in formula I is a chiral center and, therefore, can exist in either the (R) or (S) configuration. According to one aspect, the present invention provides a compound of formula I wherein the compound is in the (R) configuration with respect to the nitrogen. In certain embodiments of the present invention, at least about 99.6%, 99.7%, 99.8%, 99.85%, 99.9%, or 99.95% of a compound of formula I is in the (R) configuration with respect to nitrogen.

As defined generally above, the X⁻ group of formula I is a suitable anion. In certain embodiments; X⁻ is the anion of a suitable Brønsted acid. Exemplary Brønsted acids include hydrogen halides, carboxylic acids, sulfonic acids, sulfuric acid, and phosphoric acid. In certain embodiments, X⁻ is chloride, bromide, iodide, fluoride, sulfate, bisulfate, tartrate, nitrate, citrate, bitartrate, carbonate, phosphate, malate, maleate, fumarate sulfonate, methylsulfonate, formate, carboxylate, sulfate, methylsulfate or succinate salt. According to one aspect, X⁻ is bromide.

It is readily apparent that a compound of formula I contains both a quaternized nitrogen group and a phenolic hydroxyl group. One of ordinary skill in the art will recognize that the phenolic hydroxyl group of a compound of formula I can form a salt with the quaternized nitrogen of a compound of formula I. Such salts can form between two molecules of a compound of formula I via an intermolecular interaction or can form between those groups of the same compound via an intramolecular interaction. The present invention contemplates both such salt forms.

In certain embodiments, the present invention provides a compound of formula I wherein R¹ is C₁₋₄ aliphatic and R² is lower alkyl. In other embodiments, the R¹ group is a (cycloalkyl)alkyl group or alkenyl group. According to certain embodiments, R¹ is cyclopropyl methyl or allyl. In other embodiments, R¹ is cyclopropyl methyl or allyl and R² is methyl.

According to one embodiment, the present invention provides a compound of formula II:

wherein X⁻ is a suitable anion as described herein.

Exemplary compounds of formula II include compound I-1 and II-2:

According to another aspect, the present invention provides a composition comprising a compound of formula III:

wherein A⁻ is a suitable anion, and at least one compound of formula I:

wherein:

-   R¹ and R² are each independently C₁₋₆ aliphatic; and -   X⁻ is a suitable anion.

As defined generally above, the A⁻ group of formula III is a suitable anion. In certain embodiments, A⁻ is the anion of a suitable Brønsted acid. Exemplary Brønsted acids include hydrogen halides, carboxylic acids, sulfonic acids, sulfuric acid, and phosphoric acid. In certain embodiments, A⁻ is chloride, bromide, iodide, fluoride, sulfate, bisulfate, tartrate, nitrate, citrate, bitartrate, carbonate, phosphate, malate, maleate, fumarate sulfonate, methylsulfonate, formate, carboxylate, sulfate, methylsulfate or succinate salt. According to one aspect, X⁻ is bromide.

It is readily apparent that a compound of formula I contains both a quaternized nitrogen group and a phenolic hydroxyl group. One of ordinary skill in the art will recognize that the phenolic hydroxyl group of a compound of formula III can form a salt with the quaternized nitrogen of a compound of formula III. Such salts can form between two molecules of a compound of formula III via an intermolecular interaction or can form between those groups of the same compound via an intramolecular interaction. The present invention contemplates both such salt forms.

International patent application publication number WO2006/127899 describes Compound II-1, (R)—N-methylnaltrexone bromide, which has the following structure:

where the compound is in the (R) configuration with respect to the nitrogen. In certain embodiments of the present invention; at least about 99.6%, 99.7%, 99.8%, 99.85%, 99.9%, or 99.95% of Compound II-1 is in the (R) configuration with respect to nitrogen. Methods for determining the amount of (R)—N-methylnaltrexone bromide, present in a sample as compared to the amount of (S)—N-methylnaltrexone bromide present in that same sample, are described in detail in WO2006/127899, the entirety of which is hereby incorporated herein by reference. In other embodiments, Compound III-1 contains 0.15% or less (S)—N-methylnaltrexone bromide.

In certain embodiments, compounds of the present invention are useful for the study of peripheral mu opioid antagonists in biological and pathological phenomena and the comparative evaluation of peripheral mu opioid antagonists.

In certain embodiments, the present invention provides a compound of the present invention in isolated form. As used herein, the term “isolated” means that a compound is provided in a form that is separated from other components that might be present in that compound's usual environment. In certain embodiments, an isolated compound is in solid form. In some embodiments, an isolated compound is at least about 50% pure as determined by a suitable HPLC method. In certain embodiments, an isolated compound is at least about 60% 70%, 80%, 90% 95%, 98%, or 99% as determined by a suitable HPLC method.

In certain embodiments, the present invention provides a composition comprising a compound of formula III:

wherein A⁻ is a suitable anion, and at least one compound of formula II:

wherein X⁻ is a suitable anion as described herein.

In other embodiments, the present invention provides a composition comprising compound III-1:

and compound II-1:

4. Uses, Formulation and Administration

As discussed above, the present invention provides a compound of formula I useful as a peripheral mu opioid receptor antagonist. According to another aspect of the present invention, pharmaceutically acceptable compositions are provided, comprising a compound of formula I, as described herein, and optionally comprising a pharmaceutically acceptable carrier, adjuvant, or vehicle. In certain embodiments of the present invention, such pharmaceutically acceptable compositions optionally further comprise one or more additional therapeutic agents.

As described above, the pharmaceutically acceptable compositions of the present invention additionally comprise a pharmaceutically acceptable carrier, adjuvant, or vehicle, which, as used herein, includes any and all solvents, diluents, or other liquid vehicle, dispersion or suspension aids, surface active agents, isotonic agents, thickening or emulsifying agents, preservatives, solid binders, lubricants and the like, as suited to the particular dosage form desired, Remingtons Pharmaceutical Sciences, 17th edition, ad. Alfonoso R. Gennaro, Mack Publishing Company, Easton, Pa. (1985) discloses various carriers used in formulating pharmaceutically acceptable compositions and known techniques for the preparation thereof. Except insofar as any conventional carrier medium is incompatible with the salt of the invention, such as by producing any undesirable biological effect or otherwise interacting in a deleterious manner with any other component(s) of the pharmaceutically acceptable composition, its use is contemplated to be within the scope of this invention. Some examples of materials which can serve as pharmaceutically acceptable carriers include, but are not limited to, ion exchangers, alumina, aluminum stearate, lecithin, serum proteins, such as human serum albumin, buffer substances such as phosphates, glycine, sorbic acid, or potassium sorbate, partial glyceride mixtures of saturated vegetable fatty acids, water, salts or electrolytes, such as protamine sulfate, disodium hydrogen phosphate, potassium hydrogen phosphate, sodium chloride, zinc salts, colloidal silica, magnesium trisilicate, polyvinyl pyrrolidone, polyacrylates, waxes, polyethylene-polyoxypropylene-block polymers, wool fat; sugars such as lactose, glucose and sucrose; starches such as corn starch and potato starch; cellulose and its derivatives such as sodium carboxymethyl cellulose, ethyl cellulose and cellulose acetate; powdered tragacanth; malt; gelatin; talc; excipients such as cocoa butter and suppository waxes; oils such as peanut oil, cottonseed oil; safflower oil; sesame oil; olive oil; corn oil and soybean oil; glycols; such a propylene glycol or polyethylene glycol; esters such as ethyl oleate and ethyl laurate; agar; buffering agents such as magnesium hydroxide and aluminum hydroxide; alginic acid; pyrogen-free water, isotonic saline; Ringer's solution; ethyl alcohol, and phosphate buffer solutions, as well as other non-toxic compatible lubricants such as sodium lauryl sulfate and magnesium stearate, as well as coloring agents, releasing agents, coating agents, sweetening, flavoring and perfuming agents, preservatives and antioxidants can also be present in the composition, according to the judgment of the formulator.

In certain embodiments, the invention relates to compositions comprising at least one compound of formula I and one or more pharmaceutically acceptable carriers, excipients, or diluents. Such compositions are prepared in accordance with acceptable pharmaceutical procedures, such as, for example, those described in Remtngtons, which is incorporated herein by reference in its entirety. Pharmaceutically acceptable carriers are those carriers that are compatible with the other ingredients in the formulation and are biologically acceptable.

The compositions of the present invention are administered orally or parenterally, neat, or in combination with conventional pharmaceutical carriers. Applicable solid carriers can include one or more substances that can also act as flavoring agents, lubricants, solubilizers, suspending agents, fillers, glidants, compression aids, binders, tablet-disintegrating agents, or encapsulating materials. In powders, the carrier is a finely divided solid that is in admixture with the finely divided active ingredient. In tablets, the active ingredient is mixed with a carrier having the necessary compression properties in suitable proportions and compacted in the shape and size desired. Suitable solid carriers include, for example, calcium phosphate, magnesium stearate, talc, sugars, lactose, dextrin, starch, gelatin, cellulose, methyl cellulose, sodium carboxymethyl cellulose, polyvinylpyrrolidine, low melting waxes and ion exchange resins.

Liquid carriers can be used in preparing solutions, suspensions, emulsions, syrups and elixirs. The active ingredient can be dissolved or suspended in a pharmaceutically acceptable liquid carrier such as water, an organic solvent, a mixture of both, or a pharmaceutically acceptable oil or fat. The liquid carrier can contain other suitable pharmaceutical additives such as, for example, solubilizers, emulsifiers, buffers, preservatives, sweeteners, flavoring agents; suspending agents, thickening agents, colors, viscosity regulators, stabilizers or osmo-regulators. Suitable examples of liquid carriers for oral and parenteral administration include water (particularly containing additives as above, e.g. cellulose derivatives, preferably sodium carboxymethyl cellulose solution), alcohols (including monohydric alcohols and polyhydric alcohols e.g. glycols) and their derivatives, and oils (e.g. fractionated coconut oil and arachis oil). For parenteral administration, the carrier can also be an oily ester such as ethyl oleate and isopropyl myristate. Sterile liquid carriers are used in sterile liquid form compositions for parenteral administration. The liquid carrier for pressurized compositions can be halogenated hydrocarbon or other pharmaceutically acceptable propellant.

Liquid pharmaceutical compositions that are sterile solutions or suspensions can be administered by, for example, intramuscular, intraperitoneal or subcutaneous injection. Sterile solutions can also be administered intravenously. Compositions for oral administration can be in either liquid or solid form.

In certain embodiments, the compositions of the present invention are administered rectally or vaginally in the form of a conventional suppository. For administration by intranasal or intrabronchial inhalation or insufflation, the compositions of the present invention can be formulated into an aqueous or partially aqueous solution, which can then be utilized in the form of an aerosol. The compositions of the present invention can also be administered transdermally through the use of a transdermal patch containing the active compound and a carrier that is inert to the active compound, is non-toxic to the skin, and allows delivery of the agent for systemic absorption into the blood stream via the skin. The carrier can take any number of forms such as creams and ointments, pastes, gels, and occlusive devices. The creams and ointments can be viscous liquid or semisolid emulsions of either the oil-in-water or water-in-oil type. Pastes comprised of absorptive powders dispersed in petroleum or hydrophilic petroleum containing the active ingredient can also be suitable. A variety of occlusive devices can be used to release the active ingredient into the blood stream such as a semipermeable membrane covering a reservoir containing the active ingredient with or without a carrier, or a matrix containing the active ingredient. Other occlusive devices are known in the literature.

Preferably the pharmaceutical composition is in unit dosage form, e.g. as tablets, capsules, powders, solutions, suspensions, emulsions, granules, or suppositories. In such form, the composition is sub-divided in unit dose containing appropriate quantities of the active ingredient; the unit dosage forms can be packaged compositions, for example, packeted powders, vials, ampoules, prefilled syringes or sachets containing liquids. The unit dosage form can be, for example, a capsule or tablet itself, or it can be the appropriate number of any such compositions in package form.

The amount of composition of the present invention provided to a patient will vary depending upon what is being administered, the purpose of the administration, such as prophylaxis or therapy, the state of the patient, the manner of administration, and the like. In therapeutic applications, compositions of the present invention are provided to a patient suffering from a condition in an amount sufficient to treat or at least partially treat the symptoms of the condition and its complications. An amount adequate to accomplish this is a “therapeutically effective amount” as described previously herein. The dosage to be used in the treatment of a specific case must be subjectively determined by the attending physician. The variables involved include the specific condition and the size, ago, and response pattern of the patient. The treatment of substance abuse follows the same method of subjective drug administration under the guidance of the attending physician. Generally, a starting dose is about 5 mg per day with gradual increase in the daily dose to about 150 mg per day, to provide the desired dosage level in the patient.

In other embodiments of the present invention, the compositions contain a compound of either of formula I or II, in an amount of at least about 97, 97.5, 98, 98.5, 99, 99.5, 99.8 weight percent where the percentages are based on the free base of said compound and on the total weight of the composition. In other embodiments, the composition containing a compound of either of formula I or II contains no more than about 2.0 area percent HPLC of total organic impurities and more preferably no more than about 1.5 area percent HPLC total organic impurities relative to the total area of the HPLC chromatogram.

In other embodiments of the present invention, a composition is provided comprising a compound of formula III, at least one compound of formula I or II, and at least one pharmaceutically acceptable carrier. In some embodiments, the compositions contain a compound of formula I or II in an amount of about 1 weight percent to about 99 weight percent, where the percentages are based on the free base of said compound and on the total weight of the composition. In other embodiments, the composition containing a compound of formula I or II contains no more than about 2.0 area percent HPLC of total organic impurities and more preferably no more than about 1.5 area percent HPLC total organic impurities relative to the total area of the HPLC chromatogram.

In certain embodiments, the present invention is directed to a composition, as described herein, comprising a prodrug of a compound of formula I. The term “prodrug,” as used herein, means a compound that is convertible in vivo by metabolic means (e.g. by hydrolysis) to a compound of formula I. Various forms of prodrugs are known in the art such as those discussed in, for example, Bundgaard, (ed.), Design of Prodrugs, Elsevier (1985); Widder, et al. (ed.), Methods in Enzymology, vol. 4, Academic Press (1985); Krogsgaard-Larsen, et al., (ed). “Design and Application of Prodrugs, Textbook of Drug Design and Development, Chapter 5, 113-191 (1991), Bundgaard, et al., Journal of Drug Delivery Reviews, 8:1-38 (1992), Bundgaard, J. of Pharmaceutical Sciences, 77:285 et seq. (1988); and Higuchi and Stella (eds.) Prodrugs as Novel Drug Delivery Systems, American Chemical Society (1975), each of which is hereby incorporated by reference in its entirety.

Combination Products and Combined Administration

In certain embodiments, inventive compositions, and formulations thereof, may be administered alone to treat one or more disorders as described herein, or alternatively may be administered in combination with (whether simultaneously or sequentially) one or more other active agents useful to treat one or more disorders as described herein. Thus, an inventive composition, or formulation thereof, can be administered concurrently with, prior to, or subsequent to, one or more active agents.

In certain embodiments, inventive compositions include, one or more other active agents in addition to a compound of formula I that is not a compound of formula I. In certain embodiments, the present invention provides a formulation that delivers a compound of formula I and at least one additional active agent.

In some embodiments, inventive formulations comprise both an opioid and a compound of formula I. Such combination products, containing both an opioid and a compound of formula I would allow simultaneous relief of pain and minimization of opioid-associated side effects (e.g., gastrointestinal effects (e.g., delayed gastric emptying, altered GI tract motility), etc.).

Opioids useful in treatment of analgesia are known in the art. For example, opioid compounds include, but are not limited to, alfentanil, anileridine, asimadoline, bremazocine, buprenorphine, butorphanol, codeine, dezocine, diacetylmorphine (heroin), dihydrocodeine, diphenoxylate, ethylmorphine, fedotozine, fentanyl, funaltrexamine, hydrocodone, hydromorphone, levallorphan, levomethadyl acetate, levorphanol, loperamide, meperidine (pethidine), methadone, morphine, morphine-6-glucoronide, nalbuphine, nalorphine, nicomorphine, opium, oxycodone, oxymorphone, papaveretum, pentazocine, propiram, propoxyphene, remifentanyl, sufentanil, tilidine, trimebutine, and tramadol. In some embodiments the opioid is at least one opioid selected from alfentanil, buprenorphine, butorphanol, codeine, dezocine, dihydrocodeine, fentanyl, hydrocodone, hydromorphone, levorphanol, meperidine (pethidine), methadone, morphine, nalbuphine, nicomorphine, oxycodone, oxymorphone, papaveretum, pentazocine, propiram, propoxyphene, sufentanil and/or tramadol. In certain embodiments of the present invention, the opioid is selected from morphine, codeine, oxycodone, hydrocodone, dihydrocodeine, propoxyphene, fentanyl, tramadol, and mixtures thereof. In a particular embodiment, the opioid is loperamide. In other embodiments, the opioid is a mixed agonist such as butorphanol. In some embodiments, the subjects are administered more than one opioid, for example, morphine and heroin or methadone and heroin.

The amount of additional active agent(s) present in combination compositions of this invention will typically be no more than the amount that would normally be administered in a composition comprising that active agent as the only therapeutic agent. In certain embodiments of the present invention, the amount of additional active agent will range from about 50% to 100% of the amount normally present in a composition comprising that compound as the only therapeutic agent.

In certain embodiments, inventive formulations may also be used in conjunction with and/or in combination with conventional therapies for gastrointestinal dysfunction to and in the amelioration of constipation and bowel dysfunction, For example, conventional therapies include, but may not be limited to functional stimulation of the intestinal tract, stool softening agents, laxatives (e.g., diphelymethane laxatives, cathartic laxatives, osmotic laxatives, saline laxatives, etc), bulk forming agents and laxatives, lubricants, intravenous hydration, and nasogastric decompression.

Uses and Kits of Inventive Formulations

As discussed above, the present invention provides a compound of formula I and pharmaceutically acceptable compositions and formulations thereof, useful in antagonizing undesirable side effects of opioid analgesic therapy (e.g., gastrointestinal effects (e.g., delayed gastric emptying, altered GI tract motility), etc.). Furthermore, a compound of formula I, and pharmaceutically acceptable compositions and formulations thereof, may be used as to treat subjects having disease states that are ameliorated by binding μ opioid receptors, or in any treatment wherein temporary suppression of the μ opioid receptor system is desired (e.g., ileus, etc.). In certain embodiments of the present invention, methods of use of formulations are in human subjects.

Accordingly, administration of a compound of formula I, or a pharmaceutically acceptable composition or formulation thereof, may be advantageous for treatment, prevention, amelioration, delay or reduction of side effects of opioid use, such as, for example, gastrointestinal dysfunction (e.g., inhibition of intestinal motility, constipation, GI sphincter constriction, nausea, emesis (vomiting), biliary spasm, opioid bowel dysfunction, colic, dysphoria, pruritus, urinary retention, depression of respiration, papillary constriction, cardiovascular effects, chest wall rigidity and cough suppression, depression of stress response, and immune suppression associated with use of narcotic analgesia, etc, or combinations thereof. Use of a compound of formula I, or a pharmaceutically acceptable composition or formulation thereof, may thus be beneficial from a quality of life standpoint for subjects receiving opioids, as well as to reduce complications arising from chronic constipation, such as hemorrhoids, appetite suppression, mucosal breakdown, sepsis, colon cancer risk, and myocardial infarction.

In some embodiments, a compound of formula I, and pharmaceutically acceptable compositions and formulations thereof are useful for administration to a subject receiving acute opioid administration. In some embodiments, provided formulations are useful for administration to patients suffering from post-operative gastrointestinal dysfunction.

In other embodiments, a compound of formula I, and pharmaceutically acceptable compositions and formulations thereof, a also useful for administration to subjects receiving chronic opioid administration (e.g., terminally ill patients receiving opioid therapy such as an AIDS patient, a cancer patient, a cardiovascular patient; subjects receiving chronic opioid therapy for pain management; subjects receiving opioid therapy for maintenance of opioid withdrawal). In some embodiments, the subject is a subject using opioid for chronic pain management. In some embodiments, the subject is a terminally ill patient. In other embodiments the subject is a person receiving opioid withdrawal maintenance therapy.

Alternative or additional uses for a compound of formula I, and pharmaceutically acceptable compositions and formulations thereof; described herein may be to treat, reduce, inhibit, or prevent effects of opioid use including, e.g., aberrant migration or proliferation of endothelial cells (e.g., vascular endothelial cells), increased angiogenesis, and increase in lethal factor production from opportunistic infectious agents (e.g., Pseudomonas aeruginosa). Additional advantageous uses of a compound of formula I, and pharmaceutically acceptable compositions and formulations thereof, include treatment of opioid-induced immune suppression, inhibition of angiogenesis, inhibition of vascular proliferation, treatment of pain, treatment of inflammatory conditions such as inflammatory bowel syndrome, treatment of infectious diseases and diseases of the musculoskeletal system such as osteoporosis, arthritis, osteitis, periostitis, myopathies, and treatment of autoimmune diseases.

In certain embodiments, a compound of formula I, and pharmaceutically acceptable compositions and formulations thereof, of the invention may be used in methods for preventing, inhibiting, reducing, delaying, diminishing or treating gastrointestinal dysfunction, including, but not limited to, irritable bowel syndrome, opioid-induced bowel dysfunction, colitis, post-operative or postpartum ileus, nausea and/or vomiting, decreased gastric motility and emptying, inhibition of the stomach, and small and/or large intestinal propulsion, increased amplitude of non-propulsive segmental contractions, constriction of sphincter of Oddi, increased anal sphincter tone, impaired reflex relaxation with rectal distention, diminished gastric, biliary, pancreatic or intestinal secretions, increased absorption of water from bowel contents, gastro-esophageal reflux, gastroparesis, cramping, bloating abdominal or epigastric pain and discomfort, constipation, idiopathic constipation, post-operative gastrointestinal dysfunction following abdominal surgery (e.g., colectomy (e.g., right hemicolectomy, left hemicolectomy, transverse hemicolectomy, colectomy takedown, low anterior resection)), and delayed absorption of orally administered medications or nutritive substances.

Provided forms of a compound of formula I, and pharmaceutically acceptable compositions and formulations thereof, are also useful in treatment of conditions including cancers involving angiogenesis, immune suppression, sickle cell anemia, vascular wounds, and retinopathy, treatment of inflammation associated disorders (e.g., irritable bowel syndrome), immune suppression, chronic inflammation.

In still further embodiments, veterinary applications (e.g., treatment of domestic animals, e.g. horse, dogs, cats, etc.) of use of a compound of formula I, and pharmaceutically acceptable compositions and formulations thereof, are provided. Thus, use of provided formulations in veterinary applications analogous to those discussed above for human subjects is contemplated. For example, inhibition of equine gastrointestinal motility, such as colic and constipation, may be fatal to a horse. Resulting pain suffered by the horse with colic can result in a death-inducing shock, while a long-term case of constipation may also cause a horse's death. Treatment of equines with peripheral opioid receptor antagonists has been described, e.g., in U.S. Patent Publication No. 20050124657 published Jan. 20, 2005.

It will also be appreciated that a compound of formula I, and pharmaceutically acceptable compositions and formulations thereof, can be employed in combination therapies, that is, a compound of formula I, and pharmaceutically acceptable compositions and formulations thereof, can be administered concurrently with, prior to, or subsequent to, one or more other desired therapeutics or medical procedures. Particular combination therapies (therapeutics or procedures) to employ in a combination regimen will take into account compatibility of the desired therapeutics and/or procedures and the desired therapeutic effect to be achieved. It will also be appreciated that therapies employed may achieve a desired effect for the same disorder (for example, a formulation may be administered concurrently with another compound used to treat the same disorder), or they may achieve different effects (e.g., control of any adverse effects). As used herein, additional therapeutic compounds which are normally administered to treat or prevent a particular disease, or condition, are known as “appropriate for the disease, or condition, being treated”.

In other embodiments, a compound of formula I, and pharmaceutically acceptable compositions and formulations thereof, and unit dose forms are useful in preparation of medicaments, including, but not limited to medicaments useful in the treatment of side effects of opioid use (e.g., gastrointestinal side effects (e.g., inhibition of intestinal motility, GI sphincter constriction, constipation) nausea, emesis, (vomiting), dysphoria, pruritus, etc.) or a combination thereof. Compounds of the present invention; and pharmaceutically acceptable compositions and formulations thereof, are useful for preparations of medicaments, useful in treatment of patients receiving acute opioid therapy (e.g., patients suffering from post-operative gastrointestinal dysfunction receiving acute opioid administration) or subjects using opioids chronically (e.g., terminally ill patients receiving opioid therapy such as an AIDS patient, a cancer patient, a cardiovascular patient; subjects receiving chronic opioid therapy for pain management; or subjects receiving opioid therapy for maintenance of opioid withdrawal). Still further, preparation of medicaments useful in the treatment of pain, treatment of inflammatory conditions such as inflammatory bowel syndrome, treatment of infectious diseases, treatment of diseases of the musculoskeletal system such as osteoporosis, arthritis, osteitis, periostitis, myopathies, treatment of autoimmune diseases and immune suppression, therapy of post-operative gastrointestinal dysfunction following abdominal surgery (e.g., colectomy (e.g., right hemicolectomy, left hemicolectomy, transverse hemicolectomy, colectomy takedown, low anterior resection), idiopathic constipation, and ileus (e.g., post-operative ileus, post-partum ileus), and treatment of disorders such as cancers involving angiogenesis, chronic inflammation and/or chronic pain, sickle cell anemia, vascular wounds, and retinopathy.

Still further encompassed by the invention are pharmaceutical packs and/or kits comprising a compound of formula I, or a pharmaceutically acceptable composition or formulation thereof, and a container (e.g., a foil or plastic package, or other suitable container). Optionally instructions for use are additionally provided in such kits.

In order that the invention described herein may be more fully understood, the following examples are set forth. It should be understood that these examples are for illustrative purposes only and are not to be construed as limiting this invention in any manner.

All features of each of the aspects of the invention apply to all other aspects mutatis mutandis.

EXEMPLIFICATION

General Procedures

Compound III-1 is prepared according to the methods described in detail in International Patent Application publication number WO2006/127899, the entirety of which is hereby incorporated herein by reference.

Example 1

Preparation of Compound II-1

A solution of compound III-1 was exposed to light in a suntest (UV radiation instrument) for 48 hours at 500 watt/hr to afford compound II-1. The quinone product was isolated via preparative HPLC and the resulting purified solid material was obtained via lyophilization of the HPLC isolate. The HPLC chromatogram of compound II-1 is depicted in FIG. 1.

Preparative HPLC was performed using the following method:

-   Column Specification Prodigy ODS-3, 15 cm×2.0 mm, 3 μm size     particles, from Phenomenex or equivalent -   Mobile Phase Strength (Isocratic): 75:25 (v/v) 0.1% TFA in     Water/Methanol -   Mobile Phase A=95:5 (v/v) 0.1% TFA in Water/Methanol -   Mobile Phase B=35:65 (v/v) 0.1% TFA in Water/Methanol -   Gradient Program:

Time (Min) % A 0 100 45 50 45.1 100 60 100

-   Column Temperature: 50° C. -   Flow 0.25 mL/minute -   Detection: UV, 280 nm

Identification/structural elucidation of compound II-1 was achieved using analytical data from HPLC-UV (PDA), HPLC-MS, and NMR of the isolated material. HPLC-UV (PDA) provided a UV spectrum that differs from the parent compound (starting material) via a shift in absorbance (λ-max) from 280 nm (compound III-1) to about 320 nm (compound II-1). The UV spectrum of compound II-1 is depicted in FIG. 2. This shift indicates the presence of additional bond conjugation and supports the bond structure presented. HPLC-MS shows that the peak observed in the HPLC has a m/z of 356 (ESI Positive) which is the same as the parent compound (compound III-1) and also supports the structure assigned.

NMR of the isolated material was performed using a DRX-400 spectrometer. The ¹H NMR spectrum is depicted in FIG. 3. Proton-proton homonucleus and proton-carbon heteronucleus long-range correlations support the structure of compound II-1. The data taken from these techniques described in their entirety support the structure of the compound produced after exposure to light energy (UV) from compound III-1 as being compound II-1.

Chemical shift assignments for the isolated compound am set forth in Table 1 below, where chemical shifts are referred to TMS (δ¹H=0.0 ppm) and DMSO-d6 (δ¹³C=39.5 ppm).

TABLE 1 Chemical shift assignments in DMSO-d6

COSY Cou- H-H δ ¹³C δ ¹H plings corre- HMBC C# (ppm) (ppm) (Hz) lation H-C correlation  1 140.8  7.41, d 9.6  2  2 (w), 3, 10, (w), 11  2 126.3  6.50, d 9.6  1  4, 10  3 180.9  4 149.1  4-OH 10.09 12  5  42.1  3.58, proR  6, 14, 16  2.67, proS  6, 12, 13  6 208.3  7  35.6  2.61, proS  8  6, 13  2.00, proR  8  33.4  1.94  7  1.94  9  67.5  4.45, d 7.1 10 10, 11, 13, 14 10 139.1  6.73 7.1 10  1, 9 (w), 12, 14, 11 131.5 12 116.4 13  42.5 14  70.7 14-OH  6.49 15  26.4  2.84 16  1.74 16  54.0  3.28 15  3.01 17  70.4  3.48 18  2.82 18  3.6  1.31 17, 19, 20 19 Not  0.76 18, 20 detected  0.55 20  2.8  0.70 18, 20  0.38 21  49.7  3.59 

We claim:
 1. A composition of a compound of formula I:

in an amount of at least about 97% by weight of the composition; and wherein R¹ and R² are each independently C₁₋₆ aliphatic; and X⁻ is a suitable anion.
 2. The composition of claim 1, wherein X⁻ is selected from the group consisting of the anion of a suitable BrØnsted acid, a hydrogen halide, a carboxylic acid, a sulfonic acid, a sulfuric acid, a phosphoric acid, chloride, bromide, iodide, fluoride, bisulfate, tartrate, nitrate, citrate, bitartrate, carbonate, phosphate, malate, maleate, fumarate, sulfonate, methylsulfonate, formate, carboxylate, sulfate, methylsulfate and succinate.
 3. The composition of claim 1, wherein R¹ is C₁₋₄ aliphatic and R² is lower alkyl.
 4. The composition of claim 1, wherein the compound is a compound of formula II, formula II-1 or formula-II-2:


5. A composition of a compound of formula I:

containing no more than 2% by HPLC area of total organic impurities relative to the total area of the HPLC chromatogram; and wherein R¹ and R² are each independently C₁₋₆ aliphatic; and X⁻ is a suitable anion.
 6. The composition of claim 5, wherein X⁻ is selected from the group consisting of the anion of a suitable BrØnsted acid, a hydrogen halide, a carboxylic acid, a sulfonic acid, a sulfuric acid, a phosphoric acid, chloride, bromide, iodide, fluoride, bisulfate, tartrate, nitrate, citrate, bitartrate, carbonate, phosphate, malate, maleate, fumarate, sulfonate, methylsulfonate, formate, carboxylate, sulfate, methylsulfate and succinate.
 7. The composition of claim 5, wherein R¹ is C₁₋₄ aliphatic and R² is lower alkyl.
 8. The composition of claim 5, wherein the compound is a compound of formula II, formula II-1 or formula-II-2:


9. A compound of formula I:

wherein at least about 99.6% of the compound is in the (R) configuration with respect to the nitrogen; and wherein R¹ and R² are each independently C₁₋₆ aliphatic; and X⁻ is a suitable anion.
 10. The compound of claim 9, wherein X⁻ is selected from the group consisting of the anion of a suitable BrØnsted acid, a hydrogen halide, a carboxylic acid, a sulfonic acid, a sulfuric acid, a phosphoric acid, chloride, bromide, iodide, fluoride, bisulfate, tartrate, nitrate, citrate, bitartrate, carbonate, phosphate, malate, maleate, fumarate, sulfonate, methylsulfonate, formate, carboxylate, sulfate, methylsulfate and succinate.
 11. The compound of claim 9, wherein R¹ is C₁₋₄ aliphatic and R² is lower alky.
 12. A pharmaceutical composition comprising the composition of claim 1 and a pharmaceutically acceptable carrier, adjuvant, or vehicle.
 13. The pharmaceutical composition of claim 12, in a unit dosage form for administration to a patient, wherein the unit dosage form is selected from the group consisting of tablets, capsules, powders, solutions, suspensions, emulsions, granules and suppositories.
 14. A method of reducing at least one side effect of opioid therapy in a subject receiving opioid treatment comprising administering to the subject the pharmaceutical composition of claim 12 in an amount effective to reduce the side effect, wherein the side effect is selected from the group consisting of depression of respiration, papillary constriction, cardiovascular effects, chest wall rigidity and cough suppression, depression of stress response, immune suppression, aberrant migration or proliferation of endothelial cells, increased angiogenesis, and increase in lethal factor production from opportunistic infection.
 15. The method of claim 14, wherein the subject is a patient receiving short term opioid administration or a patient receiving chronic opioid administration.
 16. A method of inhibiting, reducing, delaying, diminishing or treating a disorder comprising administering the pharmaceutical composition of claim 12 in an amount sufficient to treat the disorder, wherein the disorder is selected from the group consisting of irritable bowel syndrome, colitis, post-operative or postpartum ileus, nausea and/or vomiting, decreased gastric motility and emptying, inhibition of the stomach and small and/or large intestine propulsion, increased amplitude of non-propulsive segmental contractions, constriction of sphincter of Oddi, increased anal sphincter tone, impaired reflex relaxation with rectal distension, diminished gastric, biliary, pancreatic or intestinal secretions, increased adsorption of water from bowel contents, gastroesophageal reflux, gastroparesis, cramping, bloating abdominal or epigastric pain and discomfort, constipation, idiopathic constipation, post-operative gastrointestinal dysfunction, delayed adsorption of orally administered medications or nutritive substances, vascular proliferation, pain, inflammatory bowel syndrome, infectious disease, diseases of the musculoskeletal system, osteoporosis, arthritis, osteitis, periostitis, myopathies, sickle cell anemia, vascular wounds, retinopathy, inflammation associated disorder, immune suppression and chronic inflammation.
 17. The method of inhibiting, reducing, delaying, diminishing or treating a disorder of claim 16, wherein the composition is administered concurrently with, prior to, or subsequent to one or more other desired therapeutics or medical procedures.
 18. The method of inhibiting, reducing, delaying, diminishing or treating a disorder of claim 16, wherein the composition is administered by a method selected from the group consisting of orally, parenterally, neat and in combination with a carrier.
 19. A kit comprising a package containing a sealed container comprising the composition of claim 1, and instructions for use.
 20. The composition of claim 1, wherein the compound of formula I is in an amount of at least about 98% by weight of the composition.
 21. The composition of claim 1, wherein the compound of formula I is in an amount of at least about 99% by weight of the composition.
 22. The composition of claim 1, wherein the compound of formula I is in an amount of at least about 99.5% by weight of the composition.
 23. The composition of claim 1, wherein the compound of formula I is in an amount of at least about 99.8% by weight of the composition.
 24. The composition of claim 1, wherein R¹ is a (cycloalkyl)alkyl group or alkenyl group.
 25. The composition of claim 1, wherein R¹ is cyclopropyl methyl or allyl and R² is methyl.
 26. The composition of claim 5, wherein R¹ is a (cycloalkyl)alkyl group or alkenyl group.
 27. The composition of claim 5, wherein R¹ is cyclopropyl methyl or allyl and R² is methyl.
 28. The compound of claim 9, wherein at least about 99.8% of the compound of formula I is in the (R) configuration with respect to the nitrogen.
 29. The compound of claim 10, wherein at least about 99.9% of the compound of formula I is in the (R) configuration with respect to the nitrogen.
 30. The compound of claim 11, wherein at least about 99.95% of the compound of formula I is in the (R) configuration with respect to the nitrogen.
 31. The compound of claim 12, wherein X⁻ is bromide.
 32. The compound of claim 13, wherein R¹ is a (cycloalkyl)alkyl group or alkenyl group.
 33. The compound of claim 14, wherein R¹ is cyclopropyl methyl or allyl and R² is methyl.
 34. The composition of claim 1, wherein X⁻ is bromide.
 35. The composition of claim 5, containing no more than about 1.5% by HPLC area of total organic impurities relative to the total area of the HPLC chromatogram.
 36. The composition of claim 5, wherein X⁻ is bromide.
 37. The pharmaceutical composition of claim 13, further comprising an additional therapeutic agent. 